Explosive astrophysics

Physicists in their all-pervading seriousness prefer the term scalar field to quintessence . For the quintessence field is indeed indifferent to direction, like a mere number. Space has no preferred axis just as it has no preferred centre. 

The scalar field that is the object of their greatest desires and most ardent research is called the Higgs field. It arises as a logical necessity in their grand unification of the forces of nature. However, the cosmic scalar field mentioned above is of a very different nature, for it is infinitely lighter than the Higgs field. 

The expansion of the Universe is accelerating The news is too recent to accept without reserve. It must be checked again and again, in the most critical spirit, and yet with open mind, for it is of the utmost importance. 

Every region of the Universe is evolving, but the most spectacular evolution concerns its geometry. Space is expanding between clusters of galaxies. However, this cosmic picture, no matter how generous it may appear, is still far too abstract. The question of the materiality of the Earth and the sky is left unanswered. Where is the world s flesh The search for the material origins of 

Supernova Stellar explosion followed by the decay of radioactive nuclei. A whole generation of Homo astronomicus is now involved in the physics of such cataclysms. These spectacular events are now the subject of such intense scrutiny that one might say that humanity has entered the age of the supernova. 

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Finally we consider the question whether the effect of diquark condensation which occurs in the earlier stages of the compact star evolution (t 100 s) [8, 21, 22] at temperatures T Tc 20 — 50 MeV can be considered as an engine for explosive astrophysical phenomena like supernova explosions due... 

Mostefaoui, S., Lugmair, G. W. and Hoppe, P. (2005) 60Fe a heat source for planetary differentiation from a nearby supernova explosion. Astrophysical Journal, 625,271-277. 

Explosive astrophysical environments invariably lead to the production of nuclei away from stability. An understanding of the dynamics and nucleosynthesis in such environments is inextricably coupled to an understanding of the properties of the synthesized nuclei. In this talk a review is presented of the basic explosive nucleosynthesis mechanisms (s-process, r-process, n-process, p-process, and rp-process). Specific stellar model calculations are discussed and a summary of the pertinent nuclear data is presented. Possible experiments and nuclear-model calculations are suggested that could facilitate a better understanding of the astrophysical scenarios. 

Even after several decades of research [BUR57] into the mechanisms by which the elements are synthesized in stars, it is still often true that the degree to which an astrophysical environment can be understood is limited by the degree to which the underlying microscopic input nuclear physics data have been measured and understood. As new and more exotic high-temperature astronomical environments have been discovered and modeled (and as observations and models for more familiar objects have been refined) the needs for more and better data for nuclei away from stability have increased. In this brief overview, we discuss a few of the explosive astrophysical environments which are currently of interest and some of their required input nuclear data. 

This is an extremely small quantity, which combined with the also extremely small interaction of gravitational waves (GWs) with matter makes it impossible to generate and detect GW on earth. Fast conversions of solar-size masses are required to produce signals with amplitudes that could be detectable. Astrophysical sources are for instance supernova explosions or a collision of two neutron stars or black holes. 

Titanium-44 is thus an isotope of considerable astrophysical importance. Detection of its characteristic gamma line has aroused great enthusiasm amongst the nuclear astrophysics community because this isotope supplies precious clues as to the explosion mechanisms operating inside massive stars. Indeed, it allows us to determine the exact boundary between the part of the star which is imploding, to end up as a neutron star, and the part which is ejected and flies out into space, loaded with atomic nuclei manufactured by the star. It also provides... 

The path that leads from the multitude of anonymous and abstract elementary particles generated in the original explosion to the grass in the meadows, to the rain and the wind, to the infinite variety of shapes and states, to the profusion of feelings, must necessarily pass through the stars. Stars are an essential link between the primordial raw material that came out of the Big Bang and complex material with the ability to think. Nuclear astrophysics is the bridge between elementary particle physics and life. 

Star, driving force behind the chemical evolution of the galaxies, mother of atoms and of all life, gentle or explosive, let us seek to become better acquainted. Eor it is one thing to observe and record the state of atomic matter in the Universe, and quite another to explain it. It is to this Herculean task that nuclear astrophysics dedicates it best troops. And the starting-point for each sally is the Sun, our personal reference. 

In this case, we must examine the effect of an asymmetrical explosion on the final result of the self-destruction of a very massive black hole, that is, the supernova remnant and black hole. Such asymmetrical supernovas may explain a fair number of gamma bursts, which have remained a deep mystery up to now. Beams and jets are more than ever in the news in astrophysics. 

All this remains pure speculation and, in science, it is important to be cautious. 1 have nevertheless chosen to discuss the case of these very-high-energy explosions because it does illustrate some of the trends in contemporary astrophysics. In particular, it exemplifies the spectacular entry on stage of the black hole, which 1 personally regard with a dark eye. 

Up to now, the search for an astrophysical site that could sustain the r process has not brought much success, but it is certainly not for want of imagination. Mergers between two neutron stars or a neutron star and a black hole have even appeared on the list. Notwithstanding, the favourite potential site remains the supernova. However, despite a long inquiry into the matter, we are still unable to put forward a detailed mechanism to show how it would operate. Calculations with the r process in explosive conditions are notoriously difficult, but they are being pursued with courage and determination. 

Still cannot put forward a specific site for the r process which gives global agreement with measured abundances. It is also conceivable that there might be not just one r process, but two, operating in high-mass stars, but nevertheless in different mass ranges. In this respect, the current situation in astrophysics is thus unstable, even explosive ... 

Limongi, M. and Chieffi, A. (2006) The nucleosynthesis of 26A1 and 60Fe in solar metallicity stars extending in mass from 11 to 120 solar masses the hydrostatic and explosive contributions. Astrophysical Journal, 647, 483-500. 

McKee, C. F. and Ostriker, J. P. (1977) A theory of the interstellar medium three components regulated by supernova explosions in an inhomogeneous substrate. Astrophysical Journal, 218, 148-169. 

Abstract Supernovae are a prominent component of modern astrophysics. They are responsible for a major part of the chemical enrichment in the universe and the main recycling mechanism in galaxies. The physics of these explosions is fairly well, although not completely, understood. 

Manganese has but one stable isotope. Within nuclear astrophysics, a second naturally occurring isotope ofMn is radioactive. Itwas presentin the early solar system and may be detectable by its X-ray emission following supernova explosions. 

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